Cameras are utilized in the security industry for monitoring large areas, both indoor and outdoor. However, when monitoring an area for security, there may be certain parts within the camera's field of view that need to be kept private. A window or doorway to a house, for example. If these are not blocked out, security personnel could snoop on members of the public and infringe personal privacy.
Conventional security systems employ in-camera privacy masking solutions. Privacy masking involves placing an obscuring visual element, such as an opaque rectangle, over areas designated as privacy zones during video capture. The masking process is performed at the camera by software that tracks the field of view of the camera as it pans, tilts and zooms. When the field of view of the camera includes a predefined privacy zone, the software masks the portion of the field of view in which the privacy zone is located prior to transmitting the video feed to the security monitoring station.
However, one drawback to the conventional implementation of privacy zones is that the video feed is permanently altered such that the mask cannot be removed. Consequently, once a mask is placed on an area of the video feed, unmasking is not possible regardless of whether permission is granted to view the particular privacy zone.
Additionally, since a defined privacy zone is essentially a three-dimensional section originating at the camera and terminating at the area to be masked, the privacy zone encompasses all the space lying between the camera and the private area. Consequently, public spaces lying in front of the private area may be masked as well.
For example, a camera has a predefined field of view defined as a volume in which objects contained therein can be captured by the camera and displayed to an observer (not shown). When a region is masked, in actuality a volume containing the masked region is obscured as well. This masking of the volume containing the masked region is due to the fact that the image captured by the camera is a two-dimensional representation of a three-dimensional field of view. Consequently, the camera is not able to place masks in such a way that objects directly in front of a masked region remain visible.
Most of the time, loss of this portion of the field of view does not cause any concern. However, in certain situations an intruder or criminal may make use of known privacy zones to obscure suspicious or criminal activities. With conventional camera-based masking of privacy zones, there is little that can be done to reveal activities that may be occurring within the public area included within the volume of the masked region. An operator is left only with the option of finding an observation angle that includes the public area in question while excluding the privacy zone so that the public area of interest is not obscured. The shortcoming in this method is that not all viewing angles will provide adequate detail of the activities that may be occurring in the public area of interest. For example, faces of the people may not be visible from other angles making identification of the suspects difficult, if not impossible.
Consequently, a need exists for providing a better balance between protecting privacy and providing surveillance of public spaces.